U.S. Patent Application Publication No. 2012/0285756A1 and U.S. Patent Application Publication No. 2014/0158446A1 disclosed a wearable motorized device, which comprises a base for supporting the foot of a person and for holding the battery pack. The base is provided with raised side edges, raised rear edge, and two wheels of at least 5.5 inches in diameter. The two wheels are coaxially connected to the left and right sides of the raised side edges of the base plate. The wheel is having a wheel hub motor, and a motor controller is embedded therein. The base is also provided with a strap, which fastens the wearable motorized device to a shoe.
The wearable motorized device has the following shortcomings: the wearer's stability provided by the wearable motorized device is low due to the longitudinal length added to the wearer's feet, even when the wearer positions both her feet on the ground with one foot in front of the other during skating. This is so because the distance between the two feet with one in front of the other cannot be too large due to the limitation of the human body physique. It would otherwise cause awkwardness and discomfort to the wearer. As the battery pack is secured at the raised rear edge of the base plate, it greatly increases the length of the base, and the general contour of the motorized device far exceeds the contour of the shoe in the longitudinal direction. Thus, the wearer has to turn her feet sideways when ascending and descending stairs, causing awkwardness and inconvenience.